/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package org.jeecg.weixin.common.util.res;

import java.text.MessageFormat;
import java.util.*;
import java.util.concurrent.ConcurrentHashMap;

/**
 * An internationalization / localization helper class which reduces the bother
 * of handling ResourceBundles and takes care of the common cases of message
 * formating which otherwise require the creation of Object arrays and such.
 * <p>
 * <p>
 * The StringManager operates on a package basis. One StringManager per package
 * can be created and accessed via the getManager method call.
 * <p>
 * <p>
 * The StringManager will look for a ResourceBundle named by the package name
 * given plus the suffix of "LocalStrings". In practice, this means that the
 * localized information will be contained in a LocalStrings.properties file
 * located in the package directory of the classpath.
 * <p>
 * <p>
 * Please see the documentation for java.util.ResourceBundle for more
 * information.
 *
 * @author James Duncan Davidson [duncan@eng.sun.com]
 * @author James Todd [gonzo@eng.sun.com]
 * @author Mel Martinez [mmartinez@g1440.com]
 * @see java.util.ResourceBundle
 */
public class StringManager {

	private static final Map<String, Map<Locale, StringManager>> MANAGERS = new ConcurrentHashMap<>();
	private static int LOCALE_CACHE_SIZE = 10;
	/**
	 * The ResourceBundle for this StringManager.
	 */
	private final ResourceBundle bundle;
	private final Locale locale;

	/**
	 * Creates a new StringManager for a given package. This is a private method and
	 * all access to it is arbitrated by the static getManager method call so that
	 * only one StringManager per package will be created.
	 *
	 * @param packageName
	 *            Name of package to create StringManager for.
	 */
	private StringManager(String packageName, Locale locale) {
		String bundleName = packageName + ".LocalStrings";
		ResourceBundle bnd = null;
		try {
			bnd = ResourceBundle.getBundle(bundleName, locale);
		} catch (MissingResourceException ex) {
			// Try from the current loader (that's the case for trusted apps)
			// Should only be required if using a TC5 style classloader structure
			// where common != shared != server
			ClassLoader cl = Thread.currentThread().getContextClassLoader();
			if (cl != null) {
				try {
					bnd = ResourceBundle.getBundle(bundleName, locale, cl);
				} catch (MissingResourceException ex2) {
					// Ignore
				}
			}
		}
		this.bundle = bnd;
		// Get the actual locale, which may be different from the requested one
		if (this.bundle != null) {
			Locale bundleLocale = this.bundle.getLocale();
			if (bundleLocale.equals(Locale.ROOT)) {
				this.locale = Locale.ENGLISH;
			} else {
				this.locale = bundleLocale;
			}
		} else {
			this.locale = null;
		}
	}

	/**
	 * Get the StringManager for a particular package. If a manager for a package
	 * already exists, it will be reused, else a new StringManager will be created
	 * and returned.
	 *
	 * @param packageName
	 *            The package name
	 */
	public static final synchronized StringManager getManager(String packageName) {
		return getManager(packageName, Locale.getDefault());
	}

	/**
	 * Get the StringManager for a particular package and Locale. If a manager for a
	 * package/Locale combination already exists, it will be reused, else a new
	 * StringManager will be created and returned.
	 *
	 * @param packageName
	 *            The package name
	 * @param locale
	 *            The Locale
	 */
	public static final synchronized StringManager getManager(String packageName, Locale locale) {

		Map<Locale, StringManager> map = MANAGERS.get(packageName);
		if (map == null) {
			/*
			 * Don't want the HashMap to be expanded beyond LOCALE_CACHE_SIZE. Expansion
			 * occurs when size() exceeds capacity. Therefore keep size at or below
			 * capacity. removeEldestEntry() executes after insertion therefore the test for
			 * removal needs to use one less than the maximum desired size
			 *
			 */
			map = new LinkedHashMap<Locale, StringManager>(LOCALE_CACHE_SIZE, 1, true) {
				private static final long serialVersionUID = 1L;

				@Override
				protected boolean removeEldestEntry(Map.Entry<Locale, StringManager> eldest) {
					return size() > (LOCALE_CACHE_SIZE - 1);
				}
			};
			MANAGERS.put(packageName, map);
		}

		StringManager mgr = map.get(locale);
		if (mgr == null) {
			mgr = new StringManager(packageName, locale);
			map.put(locale, mgr);
		}
		return mgr;
	}

	// --------------------------------------------------------------
	// STATIC SUPPORT METHODS
	// --------------------------------------------------------------

	/**
	 * Retrieve the StringManager for a list of Locales. The first StringManager
	 * found will be returned.
	 *
	 * @param requestedLocales
	 *            the list of Locales
	 * @return the found StringManager or the default StringManager
	 */
	public static StringManager getManager(String packageName, Enumeration<Locale> requestedLocales) {
		while (requestedLocales.hasMoreElements()) {
			Locale locale = requestedLocales.nextElement();
			StringManager result = getManager(packageName, locale);
			if (result.getLocale().equals(locale)) {
				return result;
			}
		}
		// Return the default
		return getManager(packageName);
	}

	/**
	 * Get a string from the underlying resource bundle or return null if the String
	 * is not found.
	 *
	 * @param key
	 *            to desired resource String
	 * @return resource String matching <i>key</i> from underlying bundle or null if
	 *         not found.
	 * @throws IllegalArgumentException
	 *             if <i>key</i> is null.
	 */
	public String getString(String key) {
		if (key == null) {
			String msg = "key may not have a null value";

			throw new IllegalArgumentException(msg);
		}

		String str = null;

		try {
			// Avoid NPE if bundle is null and treat it like an MRE
			if (this.bundle != null) {
				str = this.bundle.getString(key);
			}
		} catch (MissingResourceException mre) {
			// bad: shouldn't mask an exception the following way:
			// str = "[cannot find message associated with key '" + key +
			// "' due to " + mre + "]";
			// because it hides the fact that the String was missing
			// from the calling code.
			// good: could just throw the exception (or wrap it in another)
			// but that would probably cause much havoc on existing
			// code.
			// better: consistent with container pattern to
			// simply return null. Calling code can then do
			// a null check.
			str = null;
		}

		return str;
	}

	/**
	 * Get a string from the underlying resource bundle and format it with the given
	 * set of arguments.
	 *
	 * @param key
	 * @param args
	 */
	public String getString(final String key, final Object... args) {
		String value = getString(key);
		if (value == null) {
			value = key;
		}

		MessageFormat mf = new MessageFormat(value);
		mf.setLocale(this.locale);
		return mf.format(args, new StringBuffer(), null).toString();
	}

	/**
	 * Identify the Locale this StringManager is associated with
	 */
	public Locale getLocale() {
		return this.locale;
	}
}
